Integrated circuit memory devices are widely used in many consumer, commercial and other applications. Non-volatile memory devices retain their stored data even when their power supplies are interrupted. The category of non-volatile memory devices includes PROM (Programmable ROM), EPROM (Erasable PROM), EEPROM (Electrically EPROM), and Flash Memory devices. These non-volatile memory devices may be used in mobile devices such as digital cameras, cellular phones, PDAs and so forth because they can have low power dissipation.
In addition, these non-volatile memory devices may be classified into two groups according to a structure of a memory cell array. One is a NAND-type flash memory device and the other is a NOR-type flash memory device. Because the NAND-type flash memory has a simple structure, it may provide relatively high memory capacity and relatively low cost as compared with the NOR-type flash memory. The NAND-type flash memory devices have been used for USB storage devices, MP3 Players and so on. In contrast, NOR-type flash memory devices may be capable of high processing speeds, so that they are widely used in cellular phones and other devices, where high processing speeds may be desired.
The NOR-type flash memory device generally removes charges generated in a previous sensing operation before reading data stored in memory cells. A conventional NOR-type flash memory device includes a bitline discharging circuit so as to remove at least some charge stored in a bitline before beginning a read operation. The bitline discharging circuit may include an NMOS transistor connected between a bitline and ground. When a bitline discharging signal is applied to the bitline discharging circuit, at least some residual charge of the bitline may be removed.
Moreover, a conventional NOR-type flash memory device may also include a data line discharging circuit for removing at least some charge stored in a data line before beginning a read operation. The data line discharging circuit may include an NMOS transistor connected between a data line and ground. When a control signal is applied to the data line discharging circuit, at least some residual charge of the data line may be removed.
The data line discharging circuit for discharging the data line may occupy a large area. Furthermore, the data line discharging circuit may also need a control signal for controlling the data line discharging circuit whenever a read operation starts.